This post was originally published by Valerie Strauss for the Washington Post.

Here, John Merrow, veteran education reporter for PBS, NPR, and dozens of national publications, writes about this key concerns about blended learning. Merrow is president of Learning Matters, a non-profit media production company, and his latest book is The Influence of Teachers . This post was published on his blog, Taking Note.

By John Merrow

At a recent meeting of The Philanthropy Roundtable, a few hundred people were wrapping their heads around “Blended Learning,” the latest and most promising next new thing in education. Most in the audience were funders focused on education, and, judging from their body language and comments, most were sold on the idea.

Quickly, blended learning is some mix of traditional classroom instruction (which in itself varies considerably) and instruction mediated by technology. The latter can be one student with a tablet or laptop, or small groups of kids working together on devices.

The best known practitioner of what everyone at the meeting shorthanded to ‘blended’ is Salman Khan, whose Khan Academy is serving 5 million unique users every month, and about 15,000 classrooms were using Mr. Khan’s lessons as part of their regular instruction. His inspiring story, already told on 60 Minutes and in Time Magazine, will be widely available next month when his book, “The One World Schoolhouse,” comes out. And he just received the McGraw Prize in Education, arguably the field’s most prestigious honor. [Merrow was a recipient of the 2012 McGraw Prize too.]

I am inclined to be a fan of blended learning because I have watched kids at work, and the contrast between what happens in too many classrooms and what blended learning makes possible is striking.

For blended learning, to soar, teachers cannot be controlling the action, and they don’t have to. They aren’t walking away, of course, but they are mentoring and monitoring and coaching, and sometimes instructing. This article speaks to that point.

However, my enthusiasm is tempered by three fears; you can call them ‘concerns’ if you like. They involve faddishness, greed, and limited vision.

Faddishness: I worry that blended learning will be increasingly vague and undefined as it grows in popularity. Right now almost everyone in education seems to be waving the blended flag, saying “We’re doing blended learning,” even if they don’t have a clue. At the Philanthropy Roundtable meeting a number of very savvy people, including Dave Levin of KIPP, emphasized that blended learning begins with, and relies upon, skilled teachers. So be skeptical when you hear educators endorse blended learning; ask a lot of questions.

Greed: The faddishness is an open invitation to hucksters, who can sense when educators are desperate to prove they are au courant. Technology is big business, and I can just hear the marketing guys pitching their products as ‘perfect’ for blended learning, blah blah blah. See Dave Levin’s comment above — it begins with teachers and teaching.

Limited Vision: My biggest fear is that blended learning is going to turn out to be just another crash and burn disappointment. This will happen unless its adherents also participate in a serious conversation about the goals of schooling. Right now it seems to me that blended learning is being used to get to the same old benchmarks, just faster and more individually. But those benchmarks — basically bubble tests — are limited and limiting.

Defenders of using blended learning to get to the accepted benchmarks say, in effect, “First things first. Let us get our low performing children to pass reading and math tests, and then we will let them loose.” But those goals — truth be told — are of dubious value. Why go there?

The potential of blended learning is vast, perhaps unlimited. Why not use it to find other pathways to a larger set of skills that includes literacy and numeracy? I’ve seen too many classrooms where the focus on basic skills is of such intensity that achieving them has become both the floor and the ceiling.

I think there’s an analogy with charter schools here. The charter school movement, which I have been following since the historic meeting at the headwaters of the Mississippi River in 1988, has been generally disappointing — most charter schools do no better than traditional schools — for three reasons. Eerily similar reasons: Greed, deception and limited vision. We know about for-profit charter groups cutting corners and paying multi-million dollar salaries to their bosses; that’s greed at work. As for deception, we know how some politicians supported (and support) charter schools as a first step toward their goal of dismantling public education, leading them to create rules that allow just about anyone to give and/or receive a charter. In some places it’s almost impossible to lose a charter, short of a felony conviction.

But it’s the limited vision in the charter world that disturbs me most. As I see it, the charter school movement has fallen into the test score obsession that entangles regular public schools. That was not the dreamers’ vision — they wanted charter schools to take risks, to try stuff and then share what works and doesn’t work with traditional public schools.

I fear that blended learning is going to fall into this trap. I believe that those who champion blended learning must be showing the rest of us how it allows students to travel new roads and reach new destinations, while their teachers ensure that they are also writing clearly, calculating accurately, et cetera.

Education needs to “measure what counts,” and the blended learning community has to be part of that conversation about what really matters.

Most classrooms and schools are outmoded ‘answer factories,’ and regurgitation is not a skill that is marketable. Kids today are growing up in a sea of information, 24/7, and schools must be helping them formulate questions, encouraging them to dig deep, to prepare them for a world which values the ability to formulate questions and then find answers to those questions. Who is going to hire young people skilled at regurgitation?

Of course, blended learning can turn out better workers for those answer factories, but what a waste that would be. But if its advocates limit their vision to merely producing kids who do well on standardized tests, blended learning will end up being yet another disappointment, and we will all lose.